Tory MP Bill Cash, chairman of the Commons European Scrutiny Committee, said: "This is a major treaty change whether it is for the eurozone 17 or the EU 27 because it fundamentally changes the relationship of Britain to the European Union. It therefore requires a referendum."

Euro-MP and Ukip leader Nigel Farage said: "If all member states are to implement treaty changes, then David Cameron must give the people of the UK the referendum he promised." In a sign of growing tensions in the Coalition, a frontbencher broke ranks to urge the Prime Minister to seize the moment.

Tory MP Conor Burns, Commons aide to Northern Ireland Secretary Owen Paterson, said: "This is the opportunity finally to get the British dog out of the federalist manger."